Acoustic building material



De- 25, 1,934*- J. H. DSLAM@ 1,985,487 ACOUSTIC BUILDING MATERIAL I Filed May 9, 1951 /3 y .n NTI Y ILL [m2 wg; m2

Jfz 0e fr 16./ Dam/Execeased tsl , retaining member, such as screen. The screen is preformed into any desired Patented Dec. 25, 1934 PATENT oFFICE ACOUSTIC BUILDING MATERIAL John H. Delaney, deceased, late of Los by Union Bank & Trust Co. Angeles, administrator, Los

Calif.

Angeles, of Los Angeles, Calif.,

assignor to the estate vof Ada W. Delaney, de-

ceased Application May9, 1931, Serial No. 536,302 5 Claims. A(Cl. 'l2-18) This invention relates to a building material and the method of making the same; and more particularly to an acoustical building block adapted for surfacing the interior of a room so as to permit the passage through andthe absorption of sound, whereby a non-reverberating effect is produced.

Due to the presentday development of sound pictures and broadcasting, it is essential to provide a room or enclosure with walls and ceiling which will not reecho sound waves in order to achieve a true, accurate and undistorted reproduction of the sound. It is also essential that such a room or enclosure be capable of absorbing the sound waves set up therein and prevent the entry of exterior sounds. In the patent to John H. Delaney, No. 1,660,745, issued Feb. 28, 1928, there is disclosed and claimed an acoustic building block comprising a porous shell having a perforated facing, and a filling of a sound absorbing substance such as rock wool, hair, cork or the like. The shell is formed of plaster, cement, or Wood having suflicient inherent structural strength -which is capable of maintaining the block in its desired predetermined form. It is accordingly apparent, that if plaster or cement ybe utilized, it is essential to form the walls of the-shell with a sufcient thickness which greatly increases the weight and cost of the finished product.

It has been found that an improved building material, which is both lighter in weight and less expensive to manufacture, can be provided by applying a facing of porous plaster to form the a wide meshed wire shape, preferably in the form of an open sided box and a facing of porous plaster is applied to the screen in a novel manner which will hereinafter be described in greater detail. The open sided box-like structure so forrned is fllled with a sound absorbing substance such as rock wool, hair, cork, loose pumice or the like and secured in any desirable manner to a Wall or ceiling.

The porous facing and the wide meshed screen permit the passage therethrough of sound Waves which are then absorbed by the sound absorbing filling. The box-like structure can be formed in any desirable size, and the facing can be given any desirable contour or ornamental effect. It is to be understood that the porous plaster facing utilized in this invention has insufficient 'inherent rigidity or structural strength capable of maintaining the form of the nished block, and that the wide-meshed screen is the sole form retaining member. The porous plaster can be colored prior to its application to the screen, or the porous plaster facing can be sprayed or painted in order to produce the desired ornamental or variegated effect.

It is therefore an object of this invention to provide an acoustic building block whch is both light in weight and inexpensive in manufacture, andV in general is an improvement of the building block described and claimed in the above mentoned patent to John H. Delaney.

It is a further object of this invention to provide an acoustical building block which can be formed in any desirable size and which presents an ornamental and pleasing appearance when applied to a wall or ceiling.

The invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of one embodiment of the invention. For this purpose there has been shown a form in the drawing accompanying and forming part of the present specification. There shall now be described this form in detail, which illustrates the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawing:-

Figure 1 is a front elevation, partly in perspective, of an acoustical building block constructed in accordance with this invention;

Fig. 2 is a transverse sectional view thereof taken substantially along the plane 2 2 of Fig. l; and

Fig. 3 is a perspective view of the open sided container embodying this invention with the sound absorbing blanket or filling removed.

In practicing this invention, there is employed a gypsum binder which has incorporated therein an effervescing material capablll of rendering the gypsum porous. This material is in the form of granules, as the granular particles when effervescing, travel through the binder due to the evolution of gas and render the binder uniformly porous. An example of this effervescng material is aluminum sulphate and calcium carbonate,

vone yof which is in granular form. The porous plaster so produced is highly adaptable for acoustical purposes due to the formation therein of innumerable and voids.

In actual manufacture, the open sided building block is produced as follows. A mold of any desired contour and size is first thoroughly greased intercommunicating pores in order to prevent the sticking thereto of the porous plaster. A wide meshed wire screen is then stamped out to conform to the contour of the mold and placed therein. This screen forms the framework or sole support for maintaining the finished product in its predetermined form. The screen framework 10 is maintained in spaced relation to the mold at a distance equal to the thickness of porous plaster facing .11 desired. As herein above pointed out, this facing has insufficient Iinherent rigidity capable of maintaining the form of the finished open-faced building block.

The porousL plaster, formed as hereinabove described is then poured into the mold on top of the Wire framework 11; and due to the spaced relationship of the screen with respect to the mold, part of the plaster sifts through the mesh of the screen into the space between the screen and mold. Due to the effervescing material in the gypsum binder, the pouring is accompanied by a constant ebullition of bubbles which continues contemporaneously with the setting of the plaster. Due to the use of granular eifervescing material, the ebullition o'f bubbles continues until the plaster has had suiiicient'time to set, thus assuring the formation of pores and voids in the set plaster.

After the plaster has set, the plaster in the interior of the wire framework 11 is scraped out or removed in any other desirable manner, until all or substantially all 'of the plaster above the wire is removed. The article so formed is light in Weight and is in the form of an open sided box (Fig. 3) comprising a wide-meshed supporting framework 10 and a porous plaster facing 11. The plaster facing is characterized by pores, voids, and holes 12 which coact or cooperate with the open meshed screen 10 to permit the free passage of sound waves into the interior of the Wall; and from the exterior to the interior of the box-like structure.

The interior of the box-like structure if now filled with a layer or blanket of a sound absorbing material 13 such as rock wool, hair, cork, loose purnice or substances having like sound absorbing properties can be applied to a wall or ceiling in any desirable manner as by wires passing through the corners of the box-like structure and tied to the studdings or the like. The sound absorbing blanket 13 acts as a retarder for the sound waves passing through the pores, voids, and holes 12. This is due to the entrapping of the sound waves in the multitude of tiny air spaces which exist in sound absorbing ma'- terial such as the blanket 13.

The framework 10 is preferably formed of a wide-meshed wire screen or reticulated metallic fabric in order to provide suitable spaces through which the sound waves may pass to the sound absorbing blanket 13 from the holes 12. Preferably, a 16 mesh screen is utilized; however, this buffer, absorber and invention is equally applicable to screens of any mesh. Itis merely essential that the mesh be of a size large enough so as to permit the free passage therethrough of sound waves. If it is desired to reinforce the wire framework 10, extra heavy reinforcing wire strands 14 may be incorporated therein. These reinforcing strands aid in maintaining any bends or corners in the iinished product and prevent the bending thereof. As is readily apparent, any great bending in the finished product would break the plaster. In addition, the reinforcing strands prevent sagging of the center of the finished product, which, if permitted, would likewise tend to break the plaster.

As hereinabove pointed out, the finished product can be given any desirable ornamental contour depending on the type of mold utilized. This ornamental appearance can be greatly augmented by the addition of a coloring pigment in the plaster mix or by spraying a definite design or variegated eiect onto the exposed face, it being merely essential that the pores, voids and holes 12 be not clogged up by the spraying material. If desired, the exposed face can be lacquered which renders the plaster waterproof and thus permits the ready cleaning thereof by means of any washing process.

The finished product formed as hereinabove described is highly ornamental and admirably suitable for use as an acoustical building block in halls, auditoriums, churches, etc.

What is claimed is:

1, An acoustical building block comprising a substantially rigid shell formed of a reticulated fabric, a porousfacing and a filling of sound absorbing material.

2. An acoustical building block comprising a substantially rigid shell formed of a wire mesh screen, a porous plaster facing and a filling of sound absorbing material.

3. An acoustical building block comprising a substantially rigid open sided shell formed of a wire fabric, a porous plaster facing and a lling of sound absorbing materia.

4. An ornamental acoustical building block comprising a substantially rigid open sided shell formed of a wire fabric, an ornamental porous plaster facing. and a lling of sound absorbing material.

5. An acoustic building block having a wire mesh shell, reinforcing members for stiiening the shell, a porous plaster layer at least partially embedding the shell, and a filling of sound absorbing material.

UNION BANK & TRUSTlCO.

OF LOS ANGELES, Administrator of the Estate of John H. Delaney,

Deceased, 7

By DON R. CAMERON',

Trust Ocer. 

